In a typical liquid heat exchanger or evaporation system, such as used in air conditioning and condenser units, it is customary to provide one or two main water headers located in superposed relation spanning the bank of tubes carrying the fluid to be cooled. A plurality of smaller tubes or branches sixteen or twenty in number extend laterally from the headers and each branch has one or more nozzles which emit fine conical sprays which impinge on the fluid carrying tubes. Fine sprays have been used because of the relatively large surface area of the droplets emitted which results in optimum evaporative cooling efficiency. Accordingly, it had been necessary to provide multiple arrays of such small, fine spray nozzles. The number of nozzles in a typical installation may be on the order of 120 which are arranged in a generally uniform spacing to obtain an overall rectangular spray pattern within the usually rectangular housing of such heat exchange units. A great deal of mist is generated by such arrays and much of this impinges on the walls of the unit or is carried upwardly by rising convection air currents requiring the use of complex mist baffles to avoid loss of cooling water. Another drawback of these fine spray nozzles is excessive orifice wear because of the high droplet velocity. It has now been found, that at low water pressures, a coarse spray composed of large, low velocity droplets does not appreciably lower evaporative efficiency where the spray pattern generated has a relatively deep or thick blanket. A distinctive nozzle pair arrangement is used whereby in a typical installation 16 or 18 nozzles will achieve approximately the same evaporative efficiency as heretofore obtained with 120 nozzles.
It is the principal object of this invention to provide an improved spray nozzle array which emits a generally rectangular and uniform spray pattern over a wide range of fluid pressures, resulting in the efficient use of large, low velocity liquid droplets emitted by substantially fewer nozzles arranged in cooperative pairs.
It is a further object of this invention to provide a nozzle arrangement of the above type in which the spray pattern, while covering a relatively large area, takes the form of a relatively thick blanket and in which there are substantial improvements in orifice wear and mist reduction.